Business Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 25, 2011	Jun. 26, 2010	Jun. 25, 2011	Jun. 26, 2010
Business Segments
Number of reportable segments			4
Sales	$ 694,960	$ 492,786	$ 1,288,021	$ 871,878
Intersegment Sales	26,351	11,227	51,463	22,917
Net sales	668,609	481,559	1,236,558	848,961
Operating Income (Loss)	68,619	37,301	113,920	68,951
Engineered Infrastructure Products segment:
Business Segments
Sales	206,417	163,352	375,347	270,358
Intersegment Sales	5,480	674	11,424	1,776
Net sales	200,937	162,678	363,923	268,582
Operating Income (Loss)	11,515	12,082	13,718	14,693
Engineered Infrastructure Products segment: \| Lighting and Traffic
Business Segments
Sales	145,538	117,375	262,849	205,486
Engineered Infrastructure Products segment: \| Access Systems
Business Segments
Sales	32,582	17,729	63,778	17,729
Engineered Infrastructure Products segment: \| Communication Structures
Business Segments
Sales	28,297	28,248	48,720	47,143
Utility Support Structures segment
Business Segments
Sales	136,560	114,838	262,207	228,066
Intersegment Sales	1,951	336	2,259	635
Net sales	134,609	114,502	259,948	227,431
Operating Income (Loss)	12,984	12,542	26,483	27,248
Utility Support Structures segment \| Steel
Business Segments
Sales	123,221	101,834	233,119	200,907
Utility Support Structures segment \| Concrete
Business Segments
Sales	13,339	13,004	29,088	27,159
Coatings segment
Business Segments
Sales	84,161	54,441	157,611	82,371
Intersegment Sales	10,926	6,453	22,431	12,217
Net sales	73,235	47,988	135,180	70,154
Operating Income (Loss)	15,070	9,884	25,362	14,416
Irrigation segment
Business Segments
Sales	183,701	112,159	334,749	220,798
Intersegment Sales	5	3	8	6
Net sales	183,696	112,156	334,741	220,792
Operating Income (Loss)	32,964	16,596	56,858	31,994
Other
Business Segments
Maximum percentage of sales of other businesses and activities to consolidated sales as basis for aggregation (as a percent)			10.00%
Sales	84,121	47,996	158,107	70,285
Intersegment Sales	7,989	3,761	15,341	8,283
Net sales	76,132	44,235	142,766	62,002
Operating Income (Loss)	11,380	8,708	20,294	12,972
Net corporate expense
Business Segments
Operating Income (Loss)	$ (15,294)	$ (22,511)	$ (28,795)	$ (32,372)

The net result for the period of deducting operating expenses from operating revenues.

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Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 5
-Section 03
-Paragraph 1

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

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- Definition

Amount of revenue from transactions with other operating segments of the same entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-Paragraph 27
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

+ Details

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The maximum percentage of sales of individual business activities to total consolidated sales of operating segments that do not meet the quantitative thresholds and thus are not classified as reportable segments.

+ Details

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- Definition

Represents the number of reportable segments of the entity.

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